Passivhaus buildings do not require any kind of heating at all because the heat losses are reduced to a bare minimum. Passive heat sources such as the sun, household appliances, human occupants and the heat extracted from the air forms a major part of the heat-demand. Supply air provides the remaining heat if the maximum heat load is lower than 10 W per a square meter of living space. In case such supply-heat suffices as the main source of heat, then only one can call a building to be a Passive House (Passivhaus in German).
A 75% drop in space heating can be achieved by Passivhaus buildings compared to the standard practiced in UK. Therefore, the Passivhaus standard helps in giving a robust method so as to help the industry in achieving a carbon reduction of around 80%, which according to the UK Government is set to be the legislative target. It also comes in to retrofit projects that achieve similar savings when it comes to space heating requirements.
Feedback and evidence till date has shown that Passivhaus buildings have been performing to its standard. This is immensely important, given the discrepancy between as-built performance and design aspiration for quite a few UK buildings.
Passivhaus Standards
• Maximum cooling demand and space heating lower than 15kWh/m sq. year or a maximum cooling or heating load of 10W/m sq.
• Maximum primary energy demand (total) of 120 kWh/m sq. Year.
• Air change rate of maximum 0.6 air changes per hour.
Refurbishment standards
• Maximum cooling demand and space heating less than 25 kWh/m sq. year or a maximum cooling and heating load of 10W/m sq.
• Maximum primary energy demand (total) of 120 kWh/m sq. year plus the heat load factor.
• Air change rate of maximum 1.0 air changes per hour.
Standard in UK
• Maximum levels of insulation.
• High performing windows (insulated frames).
• “Thermal bridge free” construction.
• Airtight building fabric.
• Mechanical ventilation with efficient heat recovery system.
Claiming the standard
It is recommended by the Passivhaus Trust that the perfect way in achieving quality assurance is by getting a certificate from a Passivhaus Certifier.
Feature of passivhaus buildings
• Clean, fresh air.
• Homogenous interior temperature.
• Slow temperature changes.
• Quick return to room temperature .
A number of certification processes have been developed by Passivhaus Institute so as to guarantee the quality of practitioners and Passivhaus buildings, they are:
• PHPP (Passivhaus Planning Package) is used in informing the process of design and to verify or access compliance with Passivhaus Standard.
• The Passivhaus buildings certification process.
• Certification for Passivhaus designers who possess the expertise in delivering Passivhaus buildings.
Quite a few organizations in UK have been authorized to issue Passivhaus Quality Assured certificate.
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